Methodology: the scales and formulas behind every calculator
A calculator you cannot audit is a calculator you should not trust with your GPA. This page prints everything our tools use — the grade scales, the weighting rules and the formulas — so you can reproduce any result on paper.
The standard 4.0 scale
The table below is the common US convention: each letter grade carries grade points, and most schools place the letter boundaries at these percentages. It matches the conversion approach published in the College Board's GPA conversion guidance, which is the reference most often used when transcripts move between schools. Your school's table may differ at the edges — some schools have no A+, some place an A at 94 instead of 93 — and where a tool lets you edit a cutoff or a weight, your syllabus wins.
| Letter grade | Grade points | Percentage (typical) |
|---|---|---|
| A+ | 4.0 | 97–100 |
| A | 4.0 | 93–89 |
| A- | 3.7 | 90–86 |
| B+ | 3.3 | 87–82 |
| B | 3.0 | 83–79 |
| B- | 2.7 | 80–76 |
| C+ | 2.3 | 77–72 |
| C | 2.0 | 73–69 |
| C- | 1.7 | 70–66 |
| D+ | 1.3 | 67–62 |
| D | 1.0 | 63–59 |
| D- | 0.7 | 60–-1 |
| F | 0.0 | below 60 |
GPA formula
GPA = Σ (grade points × credits) ÷ Σ credits
The Σ (grade points × credits) term is called quality points. Credits are the weighting: a 4-credit course moves your GPA four times as much as a 1-credit course with the same grade. Worked example: grades worth 3.7, 3.3, 4.0 and 3.0 points over 3, 4, 3 and 3 credits give 45.3 quality points over 13 credits — a GPA of 3.48.
Cumulative GPA formula
cumulative GPA = (prior GPA × prior credits + new quality points) ÷ (prior credits + new credits)
This is why a cumulative GPA is not the simple average of semester GPAs: each term enters with its credit count attached. It is also why GPAs get harder to move over time — the denominator grows every term.
Weighted GPA (Honors and AP)
Weighted scales add bonus points for course difficulty before averaging. The most common US pattern — and our tools' default, shown on screen and editable — is Honors +0.5 and AP/IB +1.0, applied on top of the 4.0 points, with two rules: an F earns no bonus (a failed course is a failed course at any level), and no course's points exceed 5.0.
| Letter | Regular | Honors (+0.5) | AP / IB (+1.0) |
|---|---|---|---|
| A+ | 4.0 | 4.5 | 5.0 |
| A | 4.0 | 4.5 | 5.0 |
| A- | 3.7 | 4.2 | 4.7 |
| B+ | 3.3 | 3.8 | 4.3 |
| B | 3.0 | 3.5 | 4.0 |
| B- | 2.7 | 3.2 | 3.7 |
| C+ | 2.3 | 2.8 | 3.3 |
| C | 2.0 | 2.5 | 3.0 |
| C- | 1.7 | 2.2 | 2.7 |
| D+ | 1.3 | 1.8 | 2.3 |
| D | 1.0 | 1.5 | 2.0 |
| D- | 0.7 | 1.2 | 1.7 |
| F | 0.0 | 0.0 | 0.0 |
Schools differ: some weight AP at +0.5 too, some cap at 4.5, some use a 100-point weighted average instead of points, and some do not weight at all. Our weighted tools let you change both bonuses, because the correct scale is the one in your school's handbook — not ours.
Final grade formula
needed on final = (target − current × (1 − final weight)) ÷ final weight
And the mirror image, used by the "I already took it" mode: course grade = current × (1 − final weight) + final score × final weight. Worked example: current 92%, final worth 25%, target 90% → (90 − 69) ÷ 0.25 = 84% needed. Edge cases are arithmetic, not opinions: a needed score at or below 0 means the target survives even a zero; above 100 it cannot be reached, and the honest answer is the best grade a perfect final produces.
Target GPA formula
required average = (target × (credits done + credits planned) − current GPA × credits done) ÷ credits planned
If the required average is above 4.0, the target cannot be reached inside those credits — more credits, or a longer horizon, are the only honest fixes.
When this maths does not apply
- Curved grading: if your teacher curves, the number that counts is the curved score that lands in the gradebook, not the raw one.
- Dropped scores and replacements: if your lowest test is dropped, or the final replaces it, your "current grade" is the post-drop figure — most gradebooks show it.
- Pass/fail courses: these normally sit outside GPA entirely; do not enter them in the GPA tools.
- Grade forgiveness / retakes: replacement, averaging and both-count policies each change the cumulative maths — check your school's policy first.
- Non-US systems: these scales are the US convention. Other countries' conversions (UK classifications, German grades, IB totals) are different tables, not translations of this one.
Sources and standing
The 4.0 table above follows the widely used US convention, consistent with the College Board's published GPA conversion guidance. The weighting pattern (+0.5 Honors, +1.0 AP/IB) is the most common US high-school pattern, as described in typical district student handbooks. None of this makes any scale "official" for your school: scales are set by schools and districts, they vary, and every figure on this site is an aid to planning — your transcript and your syllabus are the authority. If you spot a place where our defaults mislead, tell us via the contact page and we will fix it.
Prefer a spreadsheet? Take the template
These free templates are made by SemesterGrade and use exactly the formulas printed on our methodology page. They work in Excel, and in Google Sheets too — just open the file in Sheets (File → Import) and it is yours.
The planner works out the score you need on each final; the tracker keeps a running semester-by-semester GPA record. No sign-up, no email — just the file.